Live cell imaging combined with high-energy single-ion microbeam

Area of Science:

• Cellular biology
• Radiation biology
• Molecular biology

Background:

• DNA strand breaks are critical lesions that can lead to cell death or cancer if not repaired.
• High linear energy transfer (LET) ion radiation induces complex DNA damage, necessitating rapid cellular responses.
• Understanding the kinetics of DNA repair protein recruitment is crucial for assessing cellular response to radiation damage.

Purpose of the Study:

• To investigate the early and rapid cellular response to DNA damage induced by high-LET ion radiation using live cell imaging.
• To quantify the recruitment and release kinetics of the DNA repair protein XRCC1 at sites of DNA damage.
• To analyze the kinetics of XRCC1 protein dynamics in response to single high-energy ion impacts.

Main Methods:

• Establishment of an online live cell imaging system at a high-energy microbeam facility.
• Irradiation of HT1080 cells expressing XRCC1-RFP with single high-energy nickel ions.
• Time-lapse imaging to capture real-time recruitment and release of XRCC1 protein foci.

Main Results:

• The DNA strand break repair protein XRCC1 was rapidly recruited to ion hit sites within 20 seconds.
• XRCC1 foci formation reached a maximum approximately 200 seconds post-irradiation, followed by slower release.
• Dual-exponential kinetics were observed, with rate constants for recruitment and release determined.

Conclusions:

• The study demonstrates the rapid and dynamic recruitment of XRCC1 to DNA damage sites induced by high-LET radiation.
• The measured kinetics support a consecutive reaction model for XRCC1 involvement in DNA repair.
• This research provides quantitative insights into the early cellular response to ion radiation-induced DNA damage.